Isolation and characterization of novel bacteriophage vB_KpP_HS106 for Klebsiella pneumonia K2 and applications in foods

Abstract

The detection rate of Klebsiella pneumoniae in food is increasing, and it has emerged as a food pathogen. Global health is threatened due to the emergence of multidrug-resistant (MDR) and hypervirulent (hv) K. pneumoniae. Phages have a promising application as antibacterial agents and have the ability to lyse MDR strains. Hence, phage vB_KpP_HS106 against MDR-hv K. pneumoniae strains was isolated from sewage collected from a hospital. It can maintain stable activity at a pH range of 4–12 and a temperature range of 4°C to 50°C. The maximum adsorption rate of phage HS106 was found to be approximately 84.2% at 6 min. One-step growth curve analysis showed that the latent period of HS106 was 10 min and the burst size was approximately 183 PFU/cell. Furthermore, whole genome analysis indicated that the genome of phage HS106 was a double-stranded linear 76,430-bp long DNA molecule with 44% GC content. A total of 95 open reading frames were annotated in the HS106 genome, which did not contain any virulence genes or antibiotic resistance genes. Phage HS106 reduced MDR K. pneumoniae in milk by approximately 1.6 log10 CFU/mL at 25°C and in chicken by approximately 2 log10 CFU/cm3 at 25°C. Therefore, vB_KpP_HS106 is a promising alternative to antibiotics for biocontrol against multidrug-resistant K. pneumoniae in foods.

Potential of an Isolated Bacteriophage to Inactivate Klebsiella pneumoniae: Preliminary Studies to Control Urinary Tract Infections

“…Similar results have been obtained with phage K2a [42]. However, in general, the adsorption rate of phage KP1LMA is lower than in other studies for Klebsiella phages [24,42,43]. Phage LASTA and SJM3 adsorption assays showed that approximately 97 and 94%, respectively, of the phage particles were adsorbed to K. pneumoniae after 20 min [24].…”

“…Phages LASTA and SJM3 presented a higher burst size of 187 ± 37 and 155 ± 34 PFU/host cell, respectively, and a long latent period of 80 min [24]. In another study, phage HS106 presented higher burst size (183 PFU/host cell) and low latent period (10 min) [43]. However, the phage's burst size is also affected by the host, as observed by Kondo (2023) [49].…”

“…However, when an MOI of 10 was used, bacterial regrowth was delayed, and the bacterial concentration remained constant until the end of the experiment. Chen et al ( 2023) also observed that lower phage concentrations can induce bacterial regrowth more rapidly than those treated with higher concentrations [43]. The authors observed that bacterial density (OD600) increased more rapidly when incubated at a lower MOI of 1 compared to higher MOIs (10 and 100) [43].…”

“…Chen et al ( 2023) also observed that lower phage concentrations can induce bacterial regrowth more rapidly than those treated with higher concentrations [43]. The authors observed that bacterial density (OD600) increased more rapidly when incubated at a lower MOI of 1 compared to higher MOIs (10 and 100) [43]. Notably, despite the phage showing a life cycle of 100 min (between adsorption and burst), the decrease in bacterial concentrations was only observed after about 3 to 6 h in the inactivation assay.…”